1. Field of the Invention
This invention relates generally to agricultural implements which are used to till fields. More specifically, the invention is concerned with such implements which comprise a plurality of coulters or discs.
Generally speaking, tillage implements comprise a plurality of coulters or discs mounted for rotation about a common axis or a plurality of parallel axes. Often referred to as a harrow is one type of tillage implement which is pulled across a field to break up the soil in preparation for planting. In use, a harrow is prone to the accumulation of clods of dirt, plant debris and the like between its coulters. This problem is aggravated when the harrow is used in a very wet field, particularly one containing a substantial amount of clay. A number of devices have been proposed to prevent the accumulation of dirt clods and plant debris between adjacent coulters. Some of these devices are discussed below.
2. Description of the Prior Art
U.S. Pat. No. 2,045,762 discloses a cleaning pad for discs. The pad is secured to an arm which is adapted to be secured to an implement frame so as to maintain a portion of the pad in contact with the disc as it rotates. U.S. Pat. No. 2,901,049 discloses a scraper device including a bar which forms a trough adjacent to a portion of an associated disc. The trough is said to be operable to accumulate dirt from the disc as it rotates. The scraper is supposed to be positioned so that dirt accumulated in the trough acts to clean and polish the surface of the adjacent disc.
U.S. Pat. No. 3,438,448 discloses a unitary disc scraping device. The scraper includes a flat blade portion, a contiguous co-planar shank portion, and an angled mounting arm.
Tillage implements can be utilized to perform a wide variety of earth working tasks. For example, a harrow of the type disclosed in U.S. Pat. No. 509,068 comprises a plurality of harrow-discs and spacing-discs alternately arranged upon a harrow shaft. In use, the harrow is pulled over a field and the harrow discs slice through and break up the soil in the field in preparation for planting. A tillage implement could be used to cultivate around growing crops, too.
As a tillage implement is pulled across a field, soil tends to adhere to the sides of the coulters or discs. Similarly, clods of dirt and plant residue are prone to becoming lodged or wedged between adjacent coulters. As soil and residue accumulate in the space between adjacent coulters, the performance of the harrow or other disc-tool is diminished. Indeed, soil and residue can accumulate to a point where they hinder or prevent the coulters from penetrating the soil. The accumulation of soil and residue on coulter implements can be more of a problem under wet conditions than under dry conditions because wet soil is stickier than dry soil. Wet conditions tend to prevail in the springtime when fields need to be prepared for planting. Consequently, the accumulation of soil and residue in tillage implements is a substantial problem.
A tillage implement with narrow spacing between adjacent coulters operates to break up soil more efficiently than one having wider spacing between adjacent coulters. In order to minimize the number of times which a harrow must be pulled across a field to prepare the soil for planting, the spacing between adjacent coulters should be relatively narrow. However, tillage implements having a narrow spacing between adjacent coulters are more prone to the objectionable accumulation of soil and residue than coulter implements having a wider spacing between adjacent coulters. Accordingly, the spacing between adjacent coulters may represent a compromise between efficient, narrow spacing and wider spacing to avoid the accumulation of soil and residue.